This invention relates in general to devices used for cathode sputtering and in particular to a new and useful target for cathode sputtering apparatus.
The invention relates to a target plate for cathode sputtering. Such target plates are made from the material to be sputtered in a respective apparatus in which a layer of this material or, with the presence of a chemically active residual gas in the sputtering apparatus, a chemical compound of the target material with the active gas is to be deposited on substrate surfaces.
With apparatus of large capacity, the cathode plates, being bombarded with ions, are frequently exposed to a very high thermal load and must be cooled, to dissipate the thermal energy in excess. Nevertheless, with high performances, the problem arises that the cathode plates, when pressed against a cooled support while being rigidly clamped at their edges, as usual, warp due to thermal expansion and disengage from this support, so that the cooling ceases to be satisfactory and the target material is heated to a too high temperature. The material then becomes plastically deformable and may finally even melt.
To prevent a failure of this kind, it has already been attempted to braze or weld the backside of the target plate to the cooled support. Such a connection however, must be made very carefully, otherwise the target plate may still disengage from the support; in any case, this brazing or welding is expensive. Up to now, it has proved most satisfactory to firmly screw the target plate to the cooled support at the periphery and also to provide securing with screws at the center of the plate, to prevent detachment in this area.